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<div class="title">src/ca/uqac/dim/turtledb/Intersection.java</div>  </div>
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<a href="_intersection_8java.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/*-------------------------------------------------------------------------</span>
<a name="l00002"></a>00002 <span class="comment">    Simple distributed database engine</span>
<a name="l00003"></a>00003 <span class="comment">    Copyright (C) 2012  Sylvain Hallé</span>
<a name="l00004"></a>00004 <span class="comment"></span>
<a name="l00005"></a>00005 <span class="comment">    This program is free software: you can redistribute it and/or modify</span>
<a name="l00006"></a>00006 <span class="comment">    it under the terms of the GNU General Public License as published by</span>
<a name="l00007"></a>00007 <span class="comment">    the Free Software Foundation, either version 3 of the License, or</span>
<a name="l00008"></a>00008 <span class="comment">    (at your option) any later version.</span>
<a name="l00009"></a>00009 <span class="comment"></span>
<a name="l00010"></a>00010 <span class="comment">    This program is distributed in the hope that it will be useful,</span>
<a name="l00011"></a>00011 <span class="comment">    but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
<a name="l00012"></a>00012 <span class="comment">    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the</span>
<a name="l00013"></a>00013 <span class="comment">    GNU General Public License for more details.</span>
<a name="l00014"></a>00014 <span class="comment"></span>
<a name="l00015"></a>00015 <span class="comment">    You should have received a copy of the GNU General Public License</span>
<a name="l00016"></a>00016 <span class="comment">    along with this program.  If not, see &lt;http://www.gnu.org/licenses/&gt;.</span>
<a name="l00017"></a>00017 <span class="comment"> -------------------------------------------------------------------------*/</span>
<a name="l00018"></a>00018 <span class="keyword">package </span>ca.uqac.dim.turtledb;
<a name="l00019"></a>00019 
<a name="l00020"></a>00020 <span class="keyword">import</span> ca.uqac.dim.turtledb.QueryVisitor.VisitorException;
<a name="l00021"></a>00021 
<a name="l00022"></a><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection.html">00022</a> <span class="keyword">public</span> <span class="keyword">class </span><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection.html">Intersection</a> <span class="keyword">extends</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_n_ary_relation.html">NAryRelation</a>
<a name="l00023"></a>00023 {   
<a name="l00024"></a>00024 
<a name="l00025"></a>00025   @Override
<a name="l00026"></a><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection.html#a69bea9b9d758d57fe2abace2fd9ab204">00026</a>   <span class="keyword">public</span> <span class="keywordtype">void</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection.html#a69bea9b9d758d57fe2abace2fd9ab204">accept</a>(<a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_query_visitor.html">QueryVisitor</a> v) <span class="keywordflow">throws</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_query_visitor_1_1_visitor_exception.html">VisitorException</a>
<a name="l00027"></a>00027   {
<a name="l00028"></a>00028     super.acceptNAry(v);
<a name="l00029"></a>00029     v.visit(<span class="keyword">this</span>);
<a name="l00030"></a>00030   }
<a name="l00031"></a>00031   
<a name="l00032"></a><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_iterator.html">00032</a>   <span class="keyword">protected</span> <span class="keyword">class </span><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_iterator.html">IntersectionIterator</a> <span class="keyword">extends</span> NAryRelationStreamIterator
<a name="l00033"></a>00033   {
<a name="l00039"></a>00039     @Override
<a name="l00040"></a><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_iterator.html#a5053747ba4ad05a00daf5a2b99d6c4f1">00040</a>     <span class="keyword">protected</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_tuple.html">Tuple</a> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_iterator.html#a5053747ba4ad05a00daf5a2b99d6c4f1">internalNext</a>()
<a name="l00041"></a>00041     {
<a name="l00042"></a>00042       super.initializeIteration();
<a name="l00043"></a>00043 
<a name="l00044"></a>00044       <span class="comment">// Iterate through the vector of last tuples and find</span>
<a name="l00045"></a>00045       <span class="comment">// the smallest one</span>
<a name="l00046"></a>00046       <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_tuple.html">Tuple</a> smallest_tuple = null;
<a name="l00047"></a>00047       <span class="keywordtype">boolean</span> all_equal = <span class="keyword">false</span>;
<a name="l00048"></a>00048       <span class="keywordflow">do</span>
<a name="l00049"></a>00049       {
<a name="l00050"></a>00050         all_equal = <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_iterator.html#a8c027b68d030bcb97dcf28ad7928d002">allEqual</a>();
<a name="l00051"></a>00051         smallest_tuple = super.incrementSmallestTuple();
<a name="l00052"></a>00052       } <span class="keywordflow">while</span> (!all_equal &amp;&amp; smallest_tuple != null);
<a name="l00053"></a>00053       <span class="keywordflow">return</span> smallest_tuple;
<a name="l00054"></a>00054     }
<a name="l00055"></a>00055     
<a name="l00062"></a><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_iterator.html#a8c027b68d030bcb97dcf28ad7928d002">00062</a>     <span class="keyword">protected</span> <span class="keywordtype">boolean</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_iterator.html#a8c027b68d030bcb97dcf28ad7928d002">allEqual</a>()
<a name="l00063"></a>00063     {
<a name="l00064"></a>00064       <span class="keywordtype">int</span> len = <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_n_ary_relation.html#aed20a0eb0271434efde6557d9d1064f9">m_relations</a>.size();
<a name="l00065"></a>00065       <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_tuple.html">Tuple</a> last_elem = null;
<a name="l00066"></a>00066       <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 0; i &lt; len; i++)
<a name="l00067"></a>00067       {
<a name="l00068"></a>00068         <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_tuple.html">Tuple</a> t = <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_n_ary_relation_1_1_n_ary_relation_stream_iterator.html#ade56bb547d8596cb8e923dcd727717a3">m_lastTuple</a>.elementAt(i);
<a name="l00069"></a>00069         <span class="keywordflow">if</span> (i == 0)
<a name="l00070"></a>00070         {
<a name="l00071"></a>00071           last_elem = t;
<a name="l00072"></a>00072           <span class="keywordflow">continue</span>;
<a name="l00073"></a>00073         }
<a name="l00074"></a>00074         <span class="keywordflow">if</span> (t == null)
<a name="l00075"></a>00075           <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00076"></a>00076         <span class="keywordflow">if</span> (!last_elem.<a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_tuple.html#ad5be2811554ef22301c274978350715b">equals</a>(t))
<a name="l00077"></a>00077           <span class="keywordflow">return</span> <span class="keyword">false</span>;
<a name="l00078"></a>00078       }
<a name="l00079"></a>00079       <span class="keywordflow">return</span> <span class="keyword">true</span>;
<a name="l00080"></a>00080     }
<a name="l00081"></a>00081   }
<a name="l00082"></a>00082 
<a name="l00083"></a>00083   @Override
<a name="l00084"></a><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection.html#abf2659d27a6b03cd3eebf033406c4569">00084</a>   <span class="keyword">public</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_relation_stream_iterator.html">RelationStreamIterator</a> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection.html#abf2659d27a6b03cd3eebf033406c4569">streamIterator</a>()
<a name="l00085"></a>00085   {
<a name="l00086"></a>00086     <span class="keywordflow">return</span> <span class="keyword">new</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_iterator.html">IntersectionIterator</a>();
<a name="l00087"></a>00087   }
<a name="l00088"></a>00088 
<a name="l00089"></a>00089   @Override
<a name="l00090"></a><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection.html#a2f35542d8d81760650d7a7ec2acd4e3b">00090</a>   <span class="keyword">public</span> <a class="code" href="interfaceca_1_1uqac_1_1dim_1_1turtledb_1_1_relation_iterator.html">RelationIterator</a> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection.html#a2f35542d8d81760650d7a7ec2acd4e3b">cacheIterator</a>()
<a name="l00091"></a>00091   {
<a name="l00092"></a>00092     <span class="keywordflow">return</span> <span class="keyword">new</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_cache_iterator.html">IntersectionCacheIterator</a>();
<a name="l00093"></a>00093   }
<a name="l00094"></a>00094   
<a name="l00095"></a><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_cache_iterator.html">00095</a>   <span class="keyword">protected</span> <span class="keyword">class </span><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_cache_iterator.html">IntersectionCacheIterator</a> <span class="keyword">extends</span> NAryRelationCacheIterator
<a name="l00096"></a>00096   {
<a name="l00097"></a>00097     @Override
<a name="l00098"></a><a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_cache_iterator.html#aaaafb5b69c2bc5698626bb962acbd216">00098</a>     <span class="keyword">protected</span> <span class="keywordtype">void</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_intersection_1_1_intersection_cache_iterator.html#aaaafb5b69c2bc5698626bb962acbd216">getIntermediateResult</a>()
<a name="l00099"></a>00099     {
<a name="l00100"></a>00100       super.getIntermediateResult();
<a name="l00101"></a>00101       <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_table.html">Table</a> tab = <span class="keyword">new</span> <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_table.html">Table</a>(<a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_n_ary_relation.html#a7fa39c21e49765163cdb930d398f0826">getSchema</a>());
<a name="l00102"></a>00102       <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_table.html">Table</a> first_table = <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_n_ary_relation_1_1_n_ary_relation_cache_iterator.html#a6c957a6e89d5efb6cc48d8d3ce40808c">m_results</a>.firstElement();
<a name="l00103"></a>00103       <span class="keywordflow">for</span> (<a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_tuple.html">Tuple</a> t : first_table.<a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_table.html#a8d7fc7bc7d659babddbee9c10f6d3130">m_tuples</a>)
<a name="l00104"></a>00104       {
<a name="l00105"></a>00105         <span class="keywordtype">boolean</span> all_in = <span class="keyword">true</span>;
<a name="l00106"></a>00106         <span class="keywordflow">for</span> (<span class="keywordtype">int</span> i = 1; i &lt; <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_n_ary_relation_1_1_n_ary_relation_cache_iterator.html#a6c957a6e89d5efb6cc48d8d3ce40808c">m_results</a>.size(); i++)
<a name="l00107"></a>00107         {
<a name="l00108"></a>00108           <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_table.html">Table</a> tt = <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_n_ary_relation_1_1_n_ary_relation_cache_iterator.html#a6c957a6e89d5efb6cc48d8d3ce40808c">m_results</a>.elementAt(i);
<a name="l00109"></a>00109           <span class="keywordflow">if</span> (!tt.<a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_table.html#a092526a7a8d2c0630d295d0bc7f47c9a">contains</a>(t))
<a name="l00110"></a>00110           {
<a name="l00111"></a>00111             all_in = <span class="keyword">false</span>;
<a name="l00112"></a>00112             <span class="keywordflow">break</span>;
<a name="l00113"></a>00113           }
<a name="l00114"></a>00114         }
<a name="l00115"></a>00115         <span class="keywordflow">if</span> (all_in)
<a name="l00116"></a>00116           tab.<a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_table.html#ac72d81075238b6f6e8406714a12156ff">put</a>(t);
<a name="l00117"></a>00117       }
<a name="l00118"></a>00118       <a class="code" href="classca_1_1uqac_1_1dim_1_1turtledb_1_1_relation_cache_iterator.html#a9b5de1deed971c99d8f8ae46a8ef789e">m_intermediateResult</a> = tab;
<a name="l00119"></a>00119     }
<a name="l00120"></a>00120   }
<a name="l00121"></a>00121 
<a name="l00122"></a>00122 }
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